SB 191 
.K3 B5 
Copy 1 



SB 191 
.K3 B5 
Copy 1 



oc^^^^' 



>n'^ 



VITED STATES DEPARTMENT OF AGRICULTURE 

BULLETIN No. 634 




J^f^i^u 



Contribution from the Bureau of Chemistry 
CARL L. ALSBERG, Chief 




Washington, D. C. PROFESSIONAL PAPER April 4, 1918 

k PHYSICAL AND CHEMICAL STUDY OF THE KAFIR 

KERNEL. 

By George L. Bidwell, 
Chemist in Charge, Cattle Food and Grain Investigation Laboratory. 



The grains of nonsaccliarine sorghums are becoming very impor- 
tant commercially. Although heretofore largely limited in their 
use to feeding farm animals, they are now being employed in increas- 
ing amounts for human food, a matter which has been studied by the 
Office of Home Economics of the Department of Agriculture.^ Fur- 
thermore, the attention of manufacturers of alcohol and starch is 
being turned to these grains. As a basis for a process which would 
utiUze nonsaccharine sorghums, probably one of the cheapest sources 
of starch, in the manufacture of starch and feedstuffs, a study was 
made in the Bureau of Chemistry of the physical characteristics and 
chemical composition of the kafir kernel, and the various parts into 
which it might be separated by milling. Kafir was selected because 
it is typical of this class of grains, and economically as important as 
any of them. Therefore a sample of Dawn kafir (Dwarf BlackhuU), 
C. I. 340, was obtained from the Bureau of Plant Industry for this 
purpose. This sample was grown at the Cereal Field Station, 
Amarillo, Tex., in 1915, and is the same grain as that used in the 
food experiments.* 

The kafir kernel shows some interesting physical characteristics. 
It is obovoid, or broadly ellipsoid, convex on the outer or dorsal 
surface, and somewhat flattened on the inner or ventral surface. It 
might be considered as developed from a sphere by first roUing it 
in such a way as to lengthen one diameter slightly, then flattening it 
on one side. The tip is more or less pointed. Beneath the tip is the 
liilum, or point of attaclmient of the seed. The outer end usually is 
rounded, but often bears a tiny, double, claw-like point. The endo- 
sperm, the main portion of the kernel, is horny without, inclosing a 
white, starchy mass. The germ lies in a depression in the endosperm, 
near the tip of the seed. The kernel is covered with a thin skin or 
bran coat, dirty white in color, spotted or blotched with dark reddish 
brown or black. Figure 1 shows the interior structure of the seed. 

> U. S. Dept. Agr. Bui. 470, and Farmers' Bui. 559. 
17995"— 18— Bull. 634 -- " " 'J'^f*}"' 



BULLETIN" 634, U. S. DEPARTMENT OF AGRICULTURE. 



Fifty kernels of kafir were measured with a micrometer in three 
directions. As a kernel of kafir lay on a flat surface the vertical 
diameter was called the thickness; the shorter horizontal diameter, the 
width, and the long diameter, the length. The maximum and mini- 
mum as well as the average dimensions are shown in the following table : 

Table I. — Measurements of 50 kernels of dwarf black-hulled while kafir, in millimeters. 



Dimension. 


Maximum. 


Minimum. 


Average. 


Thickness 


Mm. 
2.74 
3.71 
4.57 


Mm. 
2.16 
2.95 
3.07 


Mm. 
2.46 


Width 


3.33 


Length 


3.90 








r/^Mst/£y?'S£' 



One thousand kernels of this sample weighed 23^ grams. There- 
fore, one kernel weighs o^ an average 0.0235 gram. From the 

measurements recorded in the 
table the average volume of 
these kernels . was calculated 
and found to be 16.78 cubic 
milhmeters and the surface of 
such a grain 32.98 square milli- 
meters. 

One hundred and fifty-seven 
grams of kafir were treated with 
sufficient water to loosen the 
bran and then separated with 
a dissecting needle into bran, 
germ, and endosperm. It was 
found that only enough water 
to wet the surface of the kernel 
was required and with two 
hours' standing in this condi- 
tion the bran could be removed 
easily. Regardless of the time 
of soaldng, there was always 
some difficulty in getting the 
bran loose at the tip. The 




Fig. 1.— Sections of kafir kernels showing (yl ) germ, 
(£) starchy endosperm, ( C) horny endosperm. 



separation of the germ and endosperm at that point was also difiScult 
For that reason there is probably a small amount of starch mixed with 
the germ, but special care was taken to keep tliis as small as possible. 
It was found that 6.1 per cent, by weight, of the kafir kernel was 
bran ; 10 per cent was germ ; 83.9 per cent was endosperm. This would 
amount to 1.02 cubic millimeters of bran; 1.68 cubic milhmeters of 
germ ; 1 4 . 1 cubic milhmeters of endosperm, if we assume that those three 
substances have practically the same specific gravity. On the same 
assumption the thickness of the bran would average 0.031 milfimeter. 
Surrounding the endosperm lies a very friable, more or less granular 
layer which seems to carry a large amomit of coloring matter. This 



0. of !)• 
APR 17 1918 



6^ ^ '^ 



'^6' 



THE KAFIR KERNEL. 



colored layer does not cover the germ but passes between it and the 
endosperm, as is evidenced in the very highly colored kernels where 
the germ is seen clearly through the bran by appearing lighter in color 
than the endosperm. In a small proportion, possibly 1 per cent of 
the kernels, this coloration was very pronounced. An extended study 
of this color was not made, but in extracting ground kafir in a paper 
capsule, both with ether and with chloroform, a red coloration was 
noted upon the lower part of the capsule, and this coloring matter 
was also noticeable in the solutions during the crude fiber determina- 
tion. It was thought that this coloring matter might be associated 
with tannin, but tests for this substance failed to show its presence. 
Additional tests by the Pharmacognosy and Leather and Paper 
Laboratories of this bureau confirmed these results. 

The next step in this work was the determination of the compo- 
sition of the kafir kernel and of the various products into which it 
had been separated by the method described above. It was found 
that by grinding the endosperm in a small coffee mill a rough sepa- 
ration of starchy and horny endosperm could be made. The mate- 
rial was reground through the mill several times until it would all 
pass a 20-mesh sieve; then the material that would pass a 40-mesh 
sieve was called ''starchy endosperm" (6), and the part that re- 
mained on the 40-mesh sieve was called "horny endosperm" (7). 
No. 6 was floury in appearance and No. 7 had the appearance of sand. 

An examination of sections of the seeds shows that the starchy 
part lies in the center of the endosperm, surrounded on all sides by 
the horny endosperm, except that it reaches the under side of the germ. 

The following samples were analyzed: 

(1) Sample of whole kafir. 

(2) Sample of whole kafir moistened and allowed to stand over 
night, dried and ground for analysis in order to approximate but 
somewhat intensify any changes wliich might be caused by the 
moistening of the various parts. 

(3) Pure endosperm, as defined above. 

(4) Pure germ, as defined above. 

(5) Pure bran, as defined above. 

(6) Starchy endosperm, as defined above. 

(7) Horny endosperm, as defined above. 

Table II. — The composition ofhafir and its various parts on a water-free basis. 



Sample. 


Per cent 

of whole 

kaflr. 


Ash. 


Ether 
extract. 


Crude 

protein 

(NX0.25). 


Crude 
fiber. 


Nitrogen- 
free ex- 
tract. 


Pento- 
sans. 


Starch. 


(1) Whole kafir 

(2) Whole kafir mois- 
tened and allowed 
to stand over night . 

(3) Pure endosperm.. 

(4) Pure germ 

(5) Pure bran 


100.0 

100.0 
83.9 
10.0 

0.1 

35.0 
48.9 


Per cent. 
1.8 

1.7 

.3 

13.2 

2.0 

.3 
.3 


Per cent. 
4.1 

4.2 

.7 

31.5 

6.8 

.8 

.7 


Per cent. 
12.7 

12.7 
12.7 
19.3 

4.8 

10.1 
13.7 


Per cent. 
1.8 

1.8 

.8 

3.8 

16.2 

.8 
.7 


Per cent. 
79.6 

79.6 
85.5 
32.2 
70.2 

86. 5 
83.8 


Per cent. 
3.3 

3.8 

1.9 

6.1 

18.4 

1.9 
1.6 


Per CfWY. 
61.9 

63.2 
69.3 




(6) Starchy endo- 


70 4 


(7) Horny endosperm 


68.8 



4 BULLETIN 634, U. S. DEPARTMENT OF AGRICULTURE. 

An attempt to determine galactans on these samples was made, but 
the results are omitted, since in no case were the results over 1 per 
cent and on attempting to recover the mucic acid from the precipi- 
tates none was found. 

The methods of analysis were those of the Association of Official 
Agricultural Chemists, as given in the journal of that association. 
The starch was estimated by the diastase method. 

The results on sample No. 2 show that no change whicli, could be 
detected by the analyses made was caused by soaking. 

These analyses may well be compared with those of different parts 
of the corn kernel made by Hopkins, Smith, and East ^ in their study 
of the structure of the corn kernel. In this work three samples of 
corn differentiated by the amount of protein contained, namely, low, 
medium, and high, were examined. The one containing the medium 
amount of protein has been selected for comparison with kafir, since 
it is nearest the normal. They divided the horny endosperm into 
two parts, ' ' horny gluten ' ' and ' ' horny starch.' ' These analyses have 
been combined so as to compare with kafir "horny endosperm." 
They also divided the starchy portion into ''crown starch" and "tip 
starch." These have also been combined to correspond to kafir 
"starchy endosperm." 

The following table compares the parts of the kafir kernel with the 
corresponding parts of the corn kernel: 

Table III. — Comparison of kafir and corn separations. 



Material. 


Kernel. 


Ash. 


Ether 
extract. 


Protein. 


Carbohy- 
drates. 




Per cent. 
7.39 
6.1 

55.59 
48.9 

25.49 
35.0 

11.53 
10.0 


Per cent. 
0.79 
2.0 

.44 
.3 

.26 
.3 

9.90 
13.2 


Per cent. 
0.89 
6.8 

1.15 

.7 

.24 
.8 

34.84 
31.5 


Per cent. 
3.96 
4.8 

11.85 
14.5 

7.84 
11.66 

19.80 
19.3 


Per cent. 
94.36 




86.4 


Homy endosperm: 


86.56 




84.5 


Starchy endosperm: 


91.66 


Kafir 


87.3 


Germ: 

Com 


35.46 


Kafir 


36.0 







The figures for percentage of the various parts of the corn kernel 
are taken from Table III on page 87 of the Illinois bulletin, and those 
for the composition are taken from Table I, on page 83. 

In comparing the analyses of kafir bran with corn bran, or corn 
hulls, the most noticeable difference is in ether extract. The kernel 
of corn is developed under the protection of husks, but the kernel of 
kafir grows in a somewhat exposed condition. When measuring the 
kernels it was found that they seemed slippery and it was difficult to 
hold them with a forceps. This led to the belief that the kernel 

» Illinois Agr. Exp. Sta. Bui. 87, Aug., 1903, p. 83. 



THE KAFIR KERNEL. 5 

might be covered with a protective fihn of some waxy or fatty mate- 
rial and it seemed worth while to ascertain the nature of it. A large 
quantity of whole kafir therefore was washed rapidly with ether 
and chloroform. This removed soluble material to the extent of 
one-tenth of 1 per cent. On examination this was found to contain 
16 per cent of unsaponifiable matter, which indicates that the kernel 
is probably covered with a film of waxy material. 

According to Baird ^ the amount of unsaponifiable matter in kafir 
fat is 1.7 per cent. The kafir fat studied by him, however, was a 
gasoline extract of the entire grain, and he described it as having a 
consistency like vaseline although somewhat harder. In this investi- 
gation the ether extract from the pure bran was found to be some- 
what harder than that described by Baird, and it was found that it 
hardened rapidly in the fat flasks and cracked from shrinking. The 
ether extract from the germ, on the other hand, was found to be a 
clear yellowish oil. The kafir fat described by Baird was a mixture 
of the solid extract from the bran and the liquid extract from the 
germ, as well as a small amount from the endosperm, and thus the 
material had the consistency he describes. 

In studying the analysis of the two portions of the endosperm of 
kafir and corn it will be noted that, though the protein is higher in 
the kafir, the horny endosperm in each case has more protein than 
has the starchy endos])erm. The germs of corn and kafir are very 
similar in composition. 

Table IV gives the distribution of the various constituents among 
the different parts of the kernel expressed in percentages of the total 
amount of each constituent in the entire grain: 

Table IV. — Distribution of constituents. 



Material. 



Whole 
kafir. 



Ash. 



Ether 
extract. 



Crude 

protein 

(NX6.25) 



Crude 
fiber. 



Nitrogen- 
free ex- 
tract. 



Germ 

Bran 

Starchy endosperm 
Horny endosperm. . 
Whole endosperm.. 



Per cent. 

10.0 

0.1 

35.0 

48.9 
83.9 



Per cent. 
77.9 
7.2 
6.2 
8.7 
14.9 



Per cent. 
75.2 
9.9 
6.7 
8.2 
14.9 



Per cent. 
15 5 
2.3 

28.4 
53.8 
82.2 



Per cent. 
19.1 
49.7 
14.1 
17.1 
31.2 



Per cent. 

4.1 

5.5 

38.4 

52.0 

90.4 



The results of this study show that corresponding parts of the 
kafir and corn kernels resemble each other in composition and appear- 
ance, and lead us to believe that if kafir were handled m a manner 
similar to that used in the preparation of corn products, kafir products 
might be substituted for the corresponding corn products. 



» Oklahoma Agr. Exp. Sta. Bui. 89, June, 1910. 



6 BULLETIN 634^ U. S. DEPARTMENT OF AGRICULTURE. 

PUBLICATIONS OF THE U. S. DEPARTMENT OF AGRICULTURE RELATING 
TO THE SUBJECT OF THIS BULLETIN. 

PUBLICATIONS AVAILABLE FOR FREE DISTRIBUTION BY THE DEPARTMENT. 

Breeding Millet and Sorgo for Drought Adaptation. (Department Bulletin No. 291.) 
Studies on the Digestibility of the Grain Sorghums. (Department Bulletin No. 470.) 
Experiments in Determination of Digestibility of Millets. (Department Bulletin 

No. 525.) 
Kafir as a Grain Crop. (Farmers' Bulletin No. 552.) 

Use of Corn, Kafir, and Cowpeas in the Home. (Farmers' Bulletin No. 559.) 
Uses of Sorghum Grain. (Farmers' Bulletin No. 686.) 

FOR SALE BY THE SUPERINTENDENT OF DOCUMENTS, GOVERNMENT PRINTING 
OFFICE, WASHINGTON, D. C. 

Corn, Milo, and Kafir in Southern Great Plains Area. (Department Bulletin 242.) 
Price, 5 cents. 

Saccharine Sorghums for Forage. (Farmers' Bulletin No. 246.) Price, 5 cents. 

Better Grain-Sorghum Crops. (Farmers' Bulletin No. 448.) Price, 5 cents. 

Importance and Improvement of Grain Sorghums. (Bureau of Plant Industry Bul- 
letin No. 203.) Price, 10 cents. 

Grain-Sorghum Production in San Antonio Region of Texas. (Bureau of Plant 
Industry Bulletin 237.) Price, 5 cents. 

Kaoliangs, New Group of Grain Sorghums. (Bureau of Plant Industry Bulletin No. 
253.) Price, 15 cents. 



I 



ADDITIONAL COPIES 

OF THIS PUBLICATION MAY BE PROCURED FROM 

THE SUPERINTENDENT OF DOCUMENTS 

GOVERNMENT PRINTING OFFICE 

WASHINGTON, D. C. 

AT 

5 CENTS PER COPY 
V 



WASHINGTON : GOVERNMENT PRINTING OFFICE : 1918 



LIBRftRY OF CONGRESS 



002 681 990 8 



1 TRRftRY OF CONGRESS 



